Striker Lewandowski joined the Bundesliga champions on a free transfer from Borussia Dortmund after four years in which he won two Bundesliga titles and the DFP-Pokal and reached the 2013 Champions League final.

Last season's 20-goal Bundesliga top scorer told a Bayern news conference: "I played at Dortmund for four years, and knew it was time to make the next step now. I asked myself the question: Where do I go? The answer was FC Bayern.

"[Coach] Pep Guardiola can teach me a lot of new things. I have learned a lot from [Dortmund coach] Jurgen Klopp, but it was time to move on."

He said he wanted to "get even better at FC Bayern and win even more titles," adding: "Of course I will have to work hard. It's a new season, and there are new expectations."

Lewandowski, who will replace Atletico Madrid-bound Mario Mandzukic in the Bayern attack, said he had no concerns about adapting to Guardiola's style, explaining: "I hope the system here will suit me perfectly. I can also adapt to a new tactic -- that's not a big problem.

"FC Bayern Munich had nine players in the World Cup semifinal, might have eight in the final. It just shows how big a club this is right now.

"Every season at FC Bayern is about winning titles, I know that. We will have to work hard. It's going to be good."

Bayern sporting executive Matthias Sammer praised Lewandowski as "incredibly flexible," saying he had "all the attributes that a footballer needs."